High-sensitivity Strain Sensor Research Articles

高灵敏度刻槽型长周期光纤光栅应变传感器

高灵敏度刻槽型长周期光纤光栅应变传感器

High-sensitivity strain sensor based on in-fiber rectangular air bubble

We demonstrated a unique rectangular air bubble by means of splicing two sections of standard single mode fibers together and tapering the splicing joint. Such an air bubble can be used to develop a promising high-sensitivity strain sensor based on Fabry-Perot interference. The sensitivity of the strain sensor with a cavity length of about 61 μm and a wall thickness of about 1 μm was measured to be up to 43.0 pm/με and is the highest strain sensitivity among the in-fiber FPI-based strain sensors with air cavities reported so far. Moreover, our strain sensor has a very low temperature sensitivity of about 2.0 pm/°C. Thus, the temperature-induced strain measurement error is less than 0.046 με/°C.

High-sensitivity strain sensor based on inflated long period fiber grating.

We demonstrated a high-sensitivity strain sensor based on an inflated long period fiber grating (I-LPFG). The I-LPFG was inscribed, for the first time to the best of our knowledge, by use of the pressure-assisted CO(2) laser beam scanning technique to inflate periodically air holes of a photonic crystal fiber. Such periodic inflations enhanced the sensitivity of the LPFG-based strain sensor to -5.62 pm/με. After high temperature annealing, the I-LPFG achieved a good repeatability and stability of temperature response with a sensitivity of 11.92 pm/°C.

Nanomaterial-Based Macroscale Printable Flexible Sensors

Printable electronics are of great interests for flexible and wearable devices as next generation electronics. In fact, printable electrodes and transistors have been widely studied by using organic and inorganic materials on plastic substrates1-3. To realize the practical, flexible device systems, many components such as transistors, sensors, and displays need to be integrated by using printing methods or compatible macroscale and low-cost fabrication methods. In this study, we propose printable sensor sheets using nanomaterial-based inorganic and organic solutions4,5. Especially here printable strain and temperature sensors for different kinds of applications are demonstrated on flexible substrates such as silicone rubber, PET, etc. by using a screen printer and a laser patterning technique. As a proof-of-concept, macroscale, low-cost sensor sheet in order to monitor the strain and cracking information from infrastructures and vehicles were fabricated on a silicone rubber using the screen printing method. The results exhibited that high sensitivity (~59%/Pa) strain sensor detected <10 µm displacement on a wall. This suggests that high sensitive low-cost sensor sheet can be used for the infrastructure monitoring system as an example. Furthermore, we will also talk about our recent results of a self-cleaning passivation layer for the flexible devices and more sensor applications such as an artificial electronic whiskers4 and smart bandage5. Our proposed printable flexible sensors may be applied to a variety of applications such as human interfaces, infrastructures, and vehicles.

High-sensitivity strain sensor based on in-fiber improved Fabry–Perot interferometer

We demonstrated a high-sensitivity strain sensor based on an in-fiber Fabry-Perot interferometer (FPI) with an air cavity, which was created by splicing together two sections of standard single-mode fibers. The sensitivity of this strain sensor was enhanced to 6.0 pm/με by improving the cavity length of the FPI by means of repeating arc discharges for reshaping the air cavity. Moreover, such a strain sensor has a very low temperature sensitivity of 1.1 pm/°C, which reduces the cross sensitivity between tensile strain and temperature.

Strain sensors based on chromium nanoparticle arrays

High sensitivity strain sensors have been fabricated by depositing chromium (Cr) nanoparticles between silver interdigital electrodes coated on the substrate of a flexible plastic material like polyethylene terephthalate. A gas phase cluster beam deposition system was used for the preparation of the nanoparticle arrays with a well-defined conductance. We demonstrate that the conductance of the nanoparticle arrays is dominated by the quantum transport between the closely spaced nanoparticles. Compared to the traditional metallic foil or semiconductor strain sensors, this kind of strain sensor demonstrates both a higher gauge factor, which can be as large as the order of 100, and a wider dynamic range, with a workable maximum applied strain beyond 3%.

High-sensitivity microfiber strain and force sensors

A microfiber biconically tapered from a standard optical fiber shows obvious sinusoidal oscillatory transmission spectrum due to the multimode interference, with evident blue-shifted peak wavelength when applying an axial force. Based on this force-induced spectral shift, here we experimentally demonstrate compact microfiber strain and force sensors with low optical power and high sensitivity. With a 1.5-μW probing light, measured sensitivity of a 2.5-μm-diameter microfiber for the strain and elongation sensing are 4.84pm/με and 404pm/μm respectively, with a force detection limit down to 50μN.

Laser synthesized gold nanoparticles for high sensitive strain gauges

We demonstrate high strain sensitivity property of gold nanoparticle (Au-NP) thin films fabricated on flexible polydimethylsiloxane (PDMS) substrates. This behavior is attributed to quantum tunneling effect that is highly dependent on nanoparticle separation. Au-NPs were synthesized in water by nanosecond laser ablation method. The clean surface providing high tunneling decay constant, size of the Au-NPs and Au-NPs aggregate clusters offer advantages for high sensitivity strain sensor. We prepared Au-NPs films on flexible PDMS substrate by using hands-on drop-cast method. To obtain high gauge factor (g factor), we investigated the nanoparticles concentration on the substrate. Laser-generated Au-NPs films demonstrated g factor of ∼300 for higher than 0.22% strain and ∼80 for the strain lower than 0.22% strain, which is favorably comparable to reported sensitivities for strain sensors based on Au-NPs. Mechanical characterizations for the prolonged working durations suggest long term stability of the strain sensors. We discuss several models describing conductance of films in low and high strain regimes.

Develoment of high-sensitivity wireless strain sensor for structural health monitoring

Due to their cost-effectiveness and ease of installation, wireless smart sensors (WSS) have received considerable recent attention for structural health monitoring of civil infrastructure. Though various wireless smart sensor networks (WSSN) have been successfully implemented for full-scale structural health monitoring (SHM) applications, monitoring of low-level ambient strain still remains a challenging problem for WSS due to A/D converter (ADC) resolution, inherent circuit noise, and the need for automatic operation. In this paper, the design and validation of high-precision strain sensor board for the Imote2 WSS platform and its application to SHM of a cable-stayed bridge are presented. By accurate and automated balancing of the Wheatstone bridge, signal amplification of up to 2507-times can be obtained, while keeping signal mean close to the center of the ADC span, which allows utilization of the full span of the ADC. For better applicability to SHM for real-world structures, temperature compensation and shunt calibration are also implemented. Moreover, the sensor board has been designed to accommodate a friction-type magnet strain sensor, in addition to traditional foil-type strain gages, facilitating fast and easy deployment. The wireless strain sensor board performance is verified through both laboratory-scale tests and deployment on a full-scale cable-stayed bridge.

High sensitive extrinsic fabry-perot interferometric sensor system with low cost

A high-sensitive fiber optic strain sensor system with low cost is demonstrated. The strain sensor is a microlens based high finesse Fabry-Perot interferometer, and a low-cost wavelength division coupler is used as a wavelength discriminator. A minor fluctuation of strain is changed to a power change at the output. Static strain and dynamic strain are successfully measured using the system. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53: 1491-1493, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26057

High sensitive fiber strain sensor using suspended-core fibers

A novel fiber strain sensor is proposed, based on the two-mode interference of a suspended-core fiber. A fullvectorial finite difference mode solver is employed as the numerical tool for characterizing the proposed strain sensor. The numerical results show that the proposed strain sensor has an estimated sensitivity of 0.05 rad/(m·μɛ), higher than that of the strain sensors using conventional multimode fibers, while the temperature sensitivity of the proposed sensor is relatively low.

Improved-bonding linearly chirped fiber grating for a high-sensitivity surface-mounted strain sensor

For a competitive sensor, both the sensitivity enhancement and calibration convenience are important. However, for surface-mounted fiber grating strain sensors, researchers in previous studies have seldom addressed these two capabilities simultaneously. Using the coupled-mode theory, we calculated the voltage signals from the filtered spectral-power interrogation system for a fiber Bragg grating with a glued grating or with a glue-free grating subject to different strain fields. Under a grating zone (the targeted surface), a one-dimensional linearly varied strain field, described by both the parameters of the average strain and the strain gradient, was considered. Finally, a simple and easy formula is provided (the improved-bonding linearly chirped fiber grating) to achieve both the sensitivity enhancement and calibration convenience at the same time for the strain sensor.

카본나노튜브 스트레인 센서 제작 기술

In this study, the strain sensing characteristics of single-wall carbon nanotubes(SWCNTs) networks were investigated to develop a film sensor for strain sensing. The SWCNTs film are formed on flexible substrates of poly(ethylene terephthalate) (PET) using spray process. In this manner we could control the transparency and obtain excellent uniformity of the networked SWCNT film. The carbon nanotube film is isotropic due to randomly oriented bundles of SWCNTs. Using experimental results it is shown that there is a nearly linear change in resistance across the film when it is subjected to tensile stress. The results presented in this study indicate the potential of such films for high sensitive transparent strain sensors on macro scale.

1310 半導体ひずみセンサを応用したピン型ロードセルの開発(J14-2 知的材料・構造システム(2) 計測・モニタリングI,ジョイントセッション,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

A pin-type load cell with a high-sensitivity semiconductor strain sensor for accurately measuring the load on a machine was developed. To detect shear strain in the pin, two strain sensors were bonded inside it Diffusion layers arranged at 45° to the load direction improve sensitivity to the strain field generated in the pin because they are sensitive in both the longitudinal and perpendicular directions. Performance testing indicated that this pin-type load cell has high linearity and small drift: the nonlinearity was 0.9%, the hysteresis was 1.2%, and the drift of the sensor output was 0.3%.

Low-cost high-sensitivity strain and temperature sensing using graded-index multimode fibers

We report a low-loss, low-cost high-sensitivity all-fiber strain and temperature sensor based on mode interference in graded-index multimode fibers. Blueshifts with strain and temperature sensitivities of 18.6 pm/microstrain and 58.5 pm/ degrees C have been observed. Experimental results show that smaller core diameter graded-index fibers display greater strain-induced peak wavelength shifts than larger core diameter fibers.

Study of piezoresistance in Ge xSi 1−x whiskers for sensor application

The piezoresistance of Ge x Si 1− x ( x = 0.01 – 0.05 ) solid solution whiskers with impurity concentrations in the vicinity to metal–insulator transition at the temperature range 4.2–300 K was studied. A ‘giant’ piezoresistance was found at low temperatures ( T<50 K) in the samples. The absolute magnitude of the gauge factor depends on the doping level and for the whiskers with ρ 300 K = 0.018 Ω cm it is around 3.4×10 4 at the temperature 4.2 K. The observed effect was used for design of high sensitive strain sensors.

Microdynamic Characterization of Modal Parameters for a Deployable Space Structure

Results are presented from an experimental investigation of the microdynamics of deployable space structures. The dynamic response of a representative deployable truss at submicrostrain levels of vibration was characterized in terms of modal parameters. The test article was subjected to stepped-sine sweeps through its fundamental flexible modes over a range of excitation amplitudes. High-sensitivity piezoceramic strain sensors were used in conjunction with a lock-in amplifier to measure the truss response from tens of microstrain down to one nanostrain. The results show that the values of modal frequency and damping ratio are strain dependent at high response amplitudes and strain independent at low amplitudes. It is inferred that, at microdynamic levels of excitation, the internal loads needed to overcome the joint friction are not attained. The nonlinear mechanisms in the deployable structure are, thus, not activated, resulting in a linear truss response.

High Sensitive Strain Microsensor based on Dielectric Matrix with Metal Nanoparticles

ABSTRACTA dielectric matrix, containing metal nanoparticles with interparticle spacings of 1–2 nm, is a system with tunnel mechanism of electrical conductivity. Its electrical resistance is very sensitive to deforming of matrix because it leads to changes in spaces between particles and as a result the potential barrier transperancy is varied.Different metals (Mo, Cr, Ta, Au, Pt, Bi, Al) and their films morphology structure were studied in order to get high sensitive strain sensors. Metal nanoparticles were deposited on elastic dielectric substrates. Strain coefficients were measured for a wide range of strains and temperatures. Variation of matrix structure gives possibilities to produce strain sensors with high electrical resistance and weak temperature dependence. The matrix with Au nanoparticles was found to have maximum strain coefficient (&gt;100). These sensors can be manufactured in the miniature scale (sensitive area around 1 micron or less).

High-sensitivity fibre-optic strain sensors for measuring structural distortion

A high sensitivity fibre-optic microbend strain sensor for detecting bending of large mechanical structures has been constructed; experimental data on transmission modulation against structural strain are presented. Optical time domain reflectometry for detecting strains at several structural points simultaneously by placing many sensors in tandem along a single fibre is described. Structural bend radii of greater than 5 km have been measured.

A high sensitivity semiconductor strain sensitive circuit

The application of the piezoresistive strain sensitivity of MOS transistors to a high sensitivity strain sensor is described. The basic physical mechanism involved is thought to be the variation of mobility of the charge carriers, which gives rise to a change in the gain factor, β, of the device. The non linear nature of the MOST is exploited in a 4 transistor bridge circuit configuration and a circuit using 2 transistors biassed with external constant current sources. Sensitivities up to 20 V/millistrain may be obtained with the supply voltage setting a limit to the dynamic range. The transducer circuit is limited by its drift performance and is better suited to sensing vibrations rather than steady strains.